To determine insulin kinetics and overnight glycemic control after bedtime administration of a new intermediate-acting insulin preparation called neutral protamine lispro (NPL).
We studied 12 patients with well-controlled type 1 diabetes. The study had a double-blind, randomized, crossover design. After a lead-in period of 10–14 days two experiments were carried out with an interval of 2–7 days. During these experiments overnight insulin kinetics and fasting blood glucose levels were studied after evening administration of NPH insulin and NPL. Blood glucose levels < 3.8 mmol/l were treated by means of a variable infusion of a 20% glucose solution.
A trend toward a shorter time to peak insulin concentration was observed after administration of NPL (P = 0.07). No differences between NPH and NPL were detected in the total area under the curve (AUC) for insulin, in insulin levels before breakfast, or in glucose levels before breakfast (P = 0.5, 0.6, and 0.4, respectively).
We detected no major differences between NPH and NPL in the total AUC for insulin, prebreakfast glucose levels, or prebreakfast insulin levels. Therefore, we conclude that NPH and NPL are equally effective in controlling overnight glycemia.
